Daniel dbawbatjgh



(No Model.) D. DRAWBLAUGH.

- TELEPHONE TRANSMITTER'.

.No.z98,676. Patented M.ay1s,1884j.`

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THE PEOPLES TELEPHONE COMPANY,

OF NEIN7 YORK.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 298,676, dated May 13, 1884. Application led November 12, 1883. (No model.) Patented in Belgium January 10, 1884, No. 63,802.

To all whom L may concern:

Be it known that I, DANIEL DRAWBAUGH,

of Eberlys Mill, Cumberland county, Pennsylvania, have invented a new and useful Improvement in Telephone Transmitters, of

which the following is a specification.

The invention relates to that class of telephones known as carbon transmitters 5 and itconsists in the construction and arrangement whereby it is protected from the effects of i ars and vibrations ofthe support to which it is attached, and at the same time rendered fire-proof.

In the accompanying drawings, Figure l is a front view of the instrument. Fig. 2 is a vertical section on the line m fr. Fig. 3 is a transverse section on the line y y. Fig. I is a rear View of the diaphragm with its attachments. Fig. 5 is a sectional view showing the interior construction of the induction-coil.

Similar letters of reference indicate like parts.

A is the base or back board of the instrument.

B is the inclosing box or case. This box I make entirely of metal, preferably of cast-iron. It is provided with suitable recesses or sockets on the front side to receive the electrodes, the induction-coil, and other internal mechanism, and on' its rear side I form, preferably, three sockets to receive blocks C, of rubber or other elastic' material, the said blocks entering also into corresponding sockets formed on the back board, A. The blocks C should'be inserted tightly in the sockets in the box B, and may be secured therein, if desired, by any suitable cement or fastening.

Passing through the back board, A, and into the elastic blocks C, are screws D. By this arrangement the box B is attached to the back board, A, by an elastic connection. At the same time said box has considerable weight. The consequence is that the vibrations conimunicated from the wall, partition, or other support to the back board, A, are taken up by the elastic blocks C to such an extent that they are unable to overcome the inertia ofthe heavy box B. I have found that this device is very efficacious in practice, especially where 5u the telephone is attached to a thin partition liable to be easily vibrated by persons moving in the building, or in cases where the building itself is subject to the jar of machinery or to the passing of heavy vehicles. Under these conditions it very frequently happens with ordinary telephone-transmitters that the jarring and accidental vibrations affect the electrodes, producing disagreeable sounds in the receiving-instrument and the blurring` and confusing of speech received thereby.

In the ring-groove'on the front side of the box B, I place a gasket, F, of felt or other elastic substance, against which rests the diaphragm G, which may be, as here shown, of wood or other non-conducting material, or of metal with suitably changed connections. Outside of the diaphragm is a wooden cover, E, having a mouth-piece orifice, as shown. To the rear side of the diaphragm is secured a metal cup-shaped bracket, H, which receives an annular electrode, preferably of earbon, I. On said annular piece of carbon is placed a carbon ball, J, to which is secured a metal rod, K, which passes down through the annular carbon and bracket and through a tube, L, of insulating material, inserted in the body ofthe case, to prevent the rod from coming in contact therewith. The lower end of the rod K may be provided with a knob, M. A similar knob,lN, is formed on the upper side of the spring O, the end of which spring is secured to the side of the caseB at l?. The ball J normally rests upon the annular carbon I. Q, is the induction-coil. (Shown more particularly in Fig. 5.) Instead of making the core of this coil in one continuous piece or bundle of wires, I make it in several sections, It, as shown in Fig. 5. Between the ends of these sections I place pieces of non-inductive material, S. I iind this construction increases materially the sensitiveness of the coil, and besides enables me to make it of a long narrow shape, substantially as here shown.

The circuits in the instrument proceed as follows: From the battery to the binding-post l, by the wire a to the primary of the induction-coil Q, by the wire b to the contact-piece T. This contact-piece is fastened by a screw to a plug of wood, U, Fig. 3, inserted in a roo suitable socket in the box B.v The circuit then proceeds by the contact-piece T to the contact-piece V on the diaphragm. These contact-pieces T and V come together when the diaphragm is in place. Thence by the wire c tothe bracket H, carbon I, carbon J, rod K, and thence to the spring O, Wire d, binding-post 2, and back to battery. The secondary circuit in the coil Qproceeds by wires e e to the line binding-posts 3 4, from which posts extend/wires ff to the binding-posts 5 6, to which posts a receiving-instrument may be attached. 4

The operation of the instrument is as follows: When speech is uttered in front of the diaphragm, the latter, in vibrating, causes variations in pressure'or contact between the electrodes I and J, thus modifying the current and rendering the same undulatory in form and capable of reproducing sounds uttered through the line in a receiving-instrument.

When the apparatus is intended not to be in operation, the ring of the receiving-instrument may be passed upon the arm W, thus raising the spring-arm O and so lifting the ball J out of contact with the carbon I, thus breaking the local circuit.

In another application for Letters Patent hitherto iiled by me I have described a telephone-transmitter containing electrodes in the shape of a ball and annular carbon operating in substantially the same manner herein set forth. This construction and arrangement of electrodes in a transmitting-telephone I do not herein claim. Also, in another application simultaneously led herewith I have described and claimed the novel form of induction-coil above set forth, which device I do not herein claim.

An important advantage of the metal case here described is that it is entirely rire-proof. It is Well known that powerful currents, derived from electric-light wires and from lightning, have through various causes been enabled to pass upon telephone-lines and the telephones. The effect of such currents is enormously to heat the wires of the connections and induction-coil in the instrument, and

often to set fire to the box or case of inamy vmable material and to any adjacent woodwork, thus producing a conflagration in the building. lVIy improved case being completely non-iniiammable, effectually cuts off any danger of ire being communicated from a burning telephone to other parts of a building, and limits the destruction caused to the internal parts of the instrument itself.

I am aware that a metal box or case has hitherto been employed with a magneto telephone, and this combination I do not herein claim, my invention being limited to a heavy metal box in connection with a microphonetransmitter, wherein it has special Vadvantages, as hereinbefore explained.

In another application filed by me simultaneously herewith, and numbered 111,546, I have fully described and claimed the construction of the induction-coil herein set forth. Said construction is therefore disclaimed in my present application.

I claim as my invention- 1. In a telephone-transmitter, a box or case consisting, substantially, of a block of heavy metal, iny combination with resistance-varying electrodes and circuit-connections contained in recesses or openings formed in said block, a back or base board, a` means of supporting the box or case thereon, and pieces A or blocks of elastic material inserted between said case and the base-board, substantially as described.

2. In a telephone-transmitter, the combination of aback or base board, a box or case containing resistance-varying electrodes, and one or more blocks or pieces of elastic material interposed between the base or back board, the box or case being sustained wholly by said elastic supports, substantially as described.

3. In a telephone, the combination of the box B, elastic blocks C, back board, A, and screws D, substantially as described.

DANIEL DRAVBAUGH.

Witnesses: n

FRED. M. OTT, M. W. J AooBs. 

